Certain processes such as kidney dialysis, industrial washing and the like often require a supply of water having a particular physical characteristic. For example, the water supply may be required to be free of a particular mineral or other substance, perhaps radioactive, may be required to have a certain pH or may be required to exhibit a certain conductivity characteristic. A common way in which such a supply of water is furnished to the user is to design a treatment system which is located at the site of use and which is configured to treat water to exhibit a particular characteristic.
An example of such a water treatment system is a portable exchange deionizing system which includes both cation and anion exchange tanks and, possibly, one or more mixed bed tanks. The resulting particularly pure water has a low conductivity, sometimes expressed as a high resistivity. Such systems may optionally include one or more additional tanks for particle removal. The ion exchange tanks must be replaced before or at the point at which their resin beds become depleted to the extent they are unable to provide water with the required physical characteristic. Such water treatment systems are usually supported by companies which contract with users for the purpose. These support companies often have a significant number of systems within a metropolitan area, often 50 or more, which must be reliably yet efficiently serviced.
The resulting infrastructure includes customers having treatment systems of widely varying treatment capacities and having usage rates which vary between users and from time to time with respect to a given user. Clearly, an efficient support organization will be able to schedule tank exchanges at or just prior to the time at which water quality reaches an unacceptable level. In addition, this organization will want to schedule such tank exchanges so as to permit planning of efficient service vehicle routes, to avoid unnecessarily frequent tank exchange and to avoid unacceptable deterioration of water quality as to any customer. The organization will also want the capability to centrally modify the monitoring parameters to recognize changing circumstances. The need for a central monitoring capability would be most inexpensively met by using an existing communication path.
One approach to a water treatment problem is reflected in Japanese Patent Document 85-034880/06. In the described system, the treatment medium, an adsorbent, is maintained on site and periodically fed into the treating tank. The amount of adsorbent which is introduced is computed based upon water flow rate and a comparison of an actual water quality parameter with a pre-determined quality parameter.
In U.S. Pat. No. 4,762,611, the described invention uses conductivity as the physical characteristic to be maintained. Conductivity measurements are made only during times at which the water is flowing, a feature used for battery conservancy reasons. Water conductivity is displayed to the user and it is assumed that the user can interpret the data.
In U.S. Pat. No. 3,676,336, the described system measures water conductivity at the input stage and also measures the volume of treated water flow. These parameters are periodically multiplied and totalized and when the total reaches a predetermined value, regenerated resin is provided. The system is incapable of using water volume alone as a replacement parameter nor is it capable of using measured conductivity alone for that purpose.
These systems have no doubt proven effective for their intended purpose. However, they have failed to appreciate the need for an apparatus and method which may be used to monitor a system capable of treating water for any one of several physical characteristics. They have also failed to appreciate how information related to a water treatment system may be used to efficiently manage the exchange of treatment tanks for each of a significant number of installations while yet avoiding replacement of such tanks at a frequency greater than necessary. Having failed to recognize the problem, they have likewise failed to present practical solutions.
An apparatus and method for monitoring a water treatment system which would provide information to permit highly efficient tank replacement while yet avoiding unacceptable deterioration of the key physical characteristic(s) of the treated water would be an important advance in the art.